Programming C work about polynomials

i have to do this work about polynomials, and i have to do some multiplications between two polynomials .
My problem is i have to put the formula of the polynomial after i multiplicate . and it has to be something like this :
" 1 + 2 x**2 + 3x**5"
I have to do some printf i guess, because it is not supposed to know the value of x and the values with 0 should not appear nor their x**n.